EP3441156B1 - Methods for producing a matrix for pressure forming of workpieces - Google Patents

Description

The invention relates to a method for producing a forming die for pressure forming of workpieces, in the context of which a die core of the forming die is provided on the outside with a core reinforcement in the form of a Armierungskörpers of fiber reinforced plastic such that the arranged on the die core Armierungskörper the die core in the circumferential direction of the Die core around a Arbeitsbewegungsachse of the die core, along which extends in the interior of the die core a workpiece holder of the die core, wherein the reinforcing body has a plastic matrix and a reinforcing fiber structure which is embedded in the plastic matrix and extending in the circumferential direction of the die core, wherein the reinforcing body Generation of a radial bias of the reinforcing body against the die core is applied to the die core, so that arranged on the die core Kernarmierung transversely to the Arbei tsbewegungsachse is radially biased against the die core and wherein the Armierungskörper is applied to generate a radial bias of the Armierungskörpers against the die core on the die core by a perpendicular to the Arbeitsbewegungsachse extending core cross-section of the die core against a present in a state of use of the die core utility core cross section a mounting core cross-section is reduced.

• indem der Armierungskörper als ausgehärteter Hohlkörper hergestellt wird, der in seinem Innern für den Matrizenkern eine Kernaufnahme aufweist, wobei die Kernaufnahme des Armierungskörpers eine sich bei Einbaulage des Matrizenkerns längs der Arbeitsbewegungsachse des Matrizenkerns erstreckende Kernaufnahmeachse aufweist, wobei die Kernaufnahme des Armierungskörpers längs der Kernaufnahmeachse wenigstens einseitig eine Kernaufnahmeöffnung aufweist und wobei die Kernaufnahme des Armierungskörpers in einem Montage-Ausgangszustand des Armierungskörpers einen sich senkrecht zu der Kernaufnahmeachse erstreckenden Ausgangs-Kernaufnahmequerschnitt besitzt,
• indem eine Montagebereitschaft des Armierungskörpers und des Matrizenkerns hergestellt wird und
• indem der montagebereite Armierungskörper und der montagebereite Matrizenkern gefügt werden, wobei der montagebereite Matrizenkern durch die Kernaufnahmeöffnung des montagebereiten Armierungskörpers längs der Kernaufnahmeachse in die Kernaufnahme des montagebereiten Armierungskörpers eingeführt und dadurch der Armierungskörper auf der Außenseite des Matrizenkerns angeordnet wird.

The invention further relates to a method for producing a forming die for pressure forming of workpieces, in the context of which a die core of the forming die is provided on the outside with a core reinforcement in the form of a reinforcing body of fiber reinforced plastic such that the Armierungskörper arranged on the die core the die core in Surrounding the die core around a working axis of movement of the die core, along which a workpiece holder of the die core extends inside the die core, the reinforcing body having a plastic matrix and a reinforcing fiber structure embedded in the plastic matrix and extending in the circumferential direction of the die core, wherein the Armierungskörper is applied while generating a radial bias of the Armierungskörpers against the die core on the die core, so that arranged on the die core Kernarmierung transversely is radially biased to the working movement axis against the die core and wherein the reinforcing body is applied to the die core to produce a radial bias of the reinforcing body against the die core,

• in that the reinforcing body is produced as a hardened hollow body which has a core receptacle in its interior for the die core, the core receptacle of the reinforcing body having a core receiving axis extending along the working movement axis of the die core in the installed position of the die core, the core receptacle of the reinforcing body being at least one side along the core receiving axis has a core receiving opening and wherein the core receptacle of the reinforcing body has an output core receiving cross section extending perpendicularly to the core receiving axis in a mounting initial state of the reinforcing body,
• by an assembly readiness of the Armierungskörpers and the die core is made and
• by fitting the ready-to-install armoring body and the ready-to-install die core, the ready-to-install die core being inserted through the core receiving opening of the ready-to-use arming body along the core receiving axis into the core receptacle of the ready-to-mount armoring body, thereby placing the armor body on the outside of the die core.

When pressure forming of workpieces by means of a forming die, the workpiece to be formed is arranged in the workpiece holder in the interior of a die core. The wall of the workpiece holder of the die core is formed shaping and provided for this purpose, for example, with a shaping profile. During the forming process, the die core and the workpiece located inside the workpiece holder of the die core are moved relative to one another along a working movement axis of the die core. Due to the process, the workpiece exerts a large radial force on the die core transversely to the working movement axis. In order to prevent undesirable deformation of the die core under the action of the radial force exerted by the workpiece, the die core is radially biased in the direction opposite to the working movement axis in the opposite direction of the radial force exerted by the workpiece. To increase its load-bearing capacity, the die core is provided with a core reinforcement, which encloses the die core on its outer side in the circumferential direction about the working movement axis.

The generic prior art is disclosed in DE 25 06 701 A1 , This document relates to a forming tool comprising a die, a Matrizenarmierung and arranged between the die and Matrizenarmierung sleeve-shaped body. The Matrizenarmierung preferably consists of carbon fibers, which are embedded in a binder. In the production of the forming tool, the die is in supercooled state inserted into the present as reinforcement ring Matrizenarmierung.

Further prior art is known from WO 99/39848 A1 , In the case of this prior art, a die core is arranged in the interior of a clamping ring which is coaxial with the die core. The clamping ring in turn is enclosed by a coaxial with the clamping ring and the die core annular steel band reinforcement in the circumferential direction. The band reinforcement is radially biased transversely to the working movement axis of the die core against the clamping ring and over the clamping ring against the die core. To accommodate large radial forces are forming dies of WO 99/39848 A1 previously known type to be provided with a large-sized and correspondingly massive armor. At a forming machine such Umformmatrizen require a large installation space, their handling is complicated by their large mass.

The object of the present invention is to provide a comparison with the generic prior art simplified method for producing a forming die for pressure forming of workpieces.

This object is achieved according to the invention by the method according to claim 1 and by the method according to claim 2.

For the die core of the forming die produced according to the claims, a core reinforcement is provided which has a reinforcing body made of fiber-reinforced plastic which is radially prestressed against the die core. The reinforcing body comprises a plastic matrix and a reinforcing fiber structure embedded in the plastic matrix and extending in the circumferential direction of the die core about its working movement axis. In the context of the claimed manufacturing process, a reinforcing body made of fiber-reinforced plastic is applied to the die core of the forming die as a core reinforcement to produce a radial prestressing of the reinforcing body against the die core on the outside of the die core.

The reinforcing fiber structure of the reinforcing body may comprise short, long or continuous fibers. The plastic matrix of the reinforcing body is in particular a polymer matrix of thermosets or thermoplastics in question.

The reinforcing body, which consists of fiber-reinforced plastic, is characterized by a high load carrying capacity and at the same time low volume and low mass out. Due to the small size, the forming die produced according to the claim can be accommodated on a forming machine to save space. The reduced mass of the forming die, for example, when handling them as part of a tool change of considerable advantage. In addition, such forming dies are cheaper than conventional forming dies for pressure forming of workpieces.

In the context of the inventive manufacturing method according to claim 1 fiber-reinforced plastic is applied in the uncured state on the outside of the die core to create a radially biased against the die core Armierungskörpers, wherein the die core at the time of application of the fiber reinforced plastic has a mounting core cross-section which is smaller as a utility core cross-section present in a use state of the die core. After curing of the fiber-reinforced plastic applied in the wet state, the reduced cross-section of the die core for the assembly is increased to the cross-section which the die core has during workpiece reshaping. Connected to the cross-sectional enlargement of the die core occurring when the reinforcing body has hardened is the generation of a radial prestressing of the hardened reinforcing body against the die core.

Alternatively, in the context of the manufacturing method according to claim 2, the reinforcing body before application to the die core as a cured hollow body. In its interior, the hardened reinforcing body has a core receptacle for the die core of the forming die according to the invention. A core receiving axis of the reinforcing body extends in the installed position of the die core in the interior of the reinforcing body along the working movement axis of the die core. Along the core receiving axis, the core receptacle of the reinforcing body has a core receiving opening at least on one side. In a mounting initial state of the reinforcing body whose core receptacle has an output core receiving cross-section. According to the invention, the core receiving cross section is increased relative to the starting core receiving cross section in order to produce a readiness for assembly of the reinforcing body and of the die core. It is thereby achieved that the core receiving cross section of the ready-to-mount Armierungskörpers is dimensioned such that the core cross-section of the ready-mounting die core is in the vertical projection on the core receiving cross-section within the core receiving cross-section and consequently the die core for applying the Armierungskörpers can be introduced into the core of the Armierungskörpers. After the preparation of the readiness for assembly of the Armierungskörpers and the die core of the ready to install Armierungskörper and the assembly-ready die core joined accordingly. In this case, the reinforcing body and the die core are moved relative to each other along the core receiving axis of the reinforcing body or along the Arbeitsbewegungsache of the die core. If the reinforcing body is arranged on the outside of the die core in the desired position after the joining process, finally the core receiving cross section of the reinforcing body is reduced. As a result, a radial prestressing of the reinforcing body is produced against the die core.

Particular embodiments of the manufacturing method according to the invention according to claims 1 and 2 emerge from the dependent claims 3 to 8.

In a further development of the method according to claim 2 is shown in claim 3 for producing a readiness for assembly of the reinforcing body and the die core of the core receiving cross section of the reinforcing body relative to the output core receiving cross-section enlarged and also reduces the core cross-section of the die core relative to the utility core cross-section. If the reinforcing body is arranged in the desired position on the outside of the die core after the joining process, finally the core receiving cross section of the reinforcing body is reduced and, in addition, the core cross section of the die core is enlarged. As a result, a radial prestressing of the reinforcing body is produced against the die core.

According to claim 4, the reinforcement body of fiber-reinforced plastic is applied directly to the die core in a preferred embodiment of the manufacturing method according to the invention according to claims 1 and 2. As a result, results as a forming die a particularly compact unit of die core and reinforcing body.

Both in the context of the inventive manufacturing method according to claim 1 and in the context of the manufacturing method according to the invention according to claim 3, it requires a reduction of the core cross-section of the die core relative to the utility core cross-section. In an advantageous embodiment of the manufacturing method according to the invention, the die core is lengthened relative to its use state along the working movement axis of the die core, preferably elastically elongated (claim 5) and / or the temperature of the die core is changed with respect to the temperature in the use state of the die core, reduced at corresponding temperature behavior of the material of the die core (claim 6).

To increase the core receiving cross section of the reinforcing body relative to the starting core receiving cross section in the manufacturing process according to claim 2, the temperature of the reinforcing body present as a cured hollow body is changed in relation to the temperature at assembly initial state of the reinforcing body, depending on the temperature behavior of the Armierkörpers increased or decreased (claim 7).

In the context of the production method according to the invention, various fiber-reinforced plastics can be used for the reinforcing body of the forming die according to the invention. Claim 8 relates to a manufacturing method according to the invention, in the context of which a reinforcing body made of carbon fiber reinforced plastic (CFRP) is applied to generate a radial bias of the reinforcing body against the die core on the die core. Carbon fiber reinforced plastics are characterized by a particularly high tensile strength at low density. The reinforcement fiber structure extending in the circumferential direction of the die core of a reinforcing body made of carbon fiber reinforced plastic applied to the die core permits, in a particularly lightweight construction, a particularly effective prestressing of the reinforcing body against the die core of the forming die according to the invention.

Are in the context of the manufacturing method according to claim 3 according to the invention a Armierungskörper of carbon fiber reinforced plastic (negative coefficient of thermal expansion) and a die core made of a material having a positive coefficient of thermal expansion, for example made of steel, and are used to produce the assembly readiness of the Armierungskörpers and the die core and / or for the production the radial bias of the Armierungskörpers against the die core changes the temperatures of the Armierungskörpers and the die core, so in each case a same temperature change of the two parts of the forming die according to the invention can be made. Because of the temperature behavior of the materials of the reinforcing body and of the die core, the mutual temperatures for producing the assembly readiness are to be reduced and to increase the radial prestressing of the reinforcing body against the die core.

Figuren 1a, 1b

Schnittdarstellungen einer Umformmatrize zum Druckumformen von Werkstücken, mit einem Matrizenkern und einer Kernarmierung,

Figur 2

den Ablauf einer ersten Variante eines Verfahrens zur Herstellung der Umformmatrize gemäß den Figuren la, 1b und

Figur 3

den Ablauf einer zweiten Variante des Verfahrens zur Herstellung der Umformmatrize gemäß den Figuren la, 1b.

The invention will be explained in more detail below with reference to exemplary schematic illustrations. Show it:

FIGS. 1a, 1b

Sectional views of a forming die for pressure forming of workpieces, with a die core and a core reinforcement,

FIG. 2

the sequence of a first variant of a method for producing the forming die according to the figures la, 1b and

FIG. 3

the sequence of a second variant of the method for producing the forming die according to the figures la, 1b.

According to FIGS. 1a, 1b, a forming die 1 for pressure forming, in the present case for the axial forming of workpieces, comprises a die core 2 made of steel and a reinforcing body 3 made of carbon fiber-reinforced plastic (CFRP). The die core 2 is hollow cylindrical and has a workpiece holder 4 in its interior. The workpiece holder 4 extends along a working movement axis 5 of the die core 2, which forms the symmetry axis of the die core 2. An axially parallel inner wall 6 of the die core 2 delimiting the workpiece holder 4 is in the usual way with a shaping profile (not shown in FIGS. 1a, 1b) Mistake. An axially parallel outer wall of the die core 2 defines a core cross section QM of the die core 2.

For pressure forming of workpieces, for example pipes, by means of the forming die 1, the workpiece arranged in the interior of the workpiece holder 4 and the forming die 1 are moved as usual along the working movement axis 5 relative to one another. The workpiece is claimed by the shaping profile of the die core 2 beyond the yield point and thereby formed.

Due to the process, the workpiece exerts a large radial force on the die core 2 during its deformation. The effective direction of the force exerted by the workpiece on the die core 2 radial force is in the FIGS. 1a, 1b illustrated by arrows.

Thus, the die core 2 is not undesirably deformed under the action of the radial force exerted by the workpiece, and the reinforcing body 3 is provided to increase the load bearing capacity of the die core 2. The reinforcing body 3 is formed in the illustrated example in the manner of a CFRP tube with a wound continuous filament structure.

The die core 2 is arranged in a core receptacle 7 of the reinforcing body 3. A core receiving axis 8 of the reinforcing body 3 coincides with the working movement axis 5 of the die core 2 in the installed position of the die core 2 in the core receptacle 7 of the reinforcing body 3. An axially parallel inner wall of the core receptacle 7 delimits a core receiving cross section QA of the reinforcing body 3.

In the FIGS. 1a, 1b is the forming die 1 and with this the die core 2 and the Armierungskörper 3 in use, in which with the forming die 1, a forming process can be performed. The reinforcing body 3 is radially biased against the die core 2 counter to the direction of the radial force exerted on the die core 2 by the workpiece during the forming process. The die core 2 has a utility core cross section, the core receptacle 7 of the reinforcing body 3 has a utility core receiving cross section.

Two ways of producing the forming die 1 are in the Figures 2 and 3 illustrated.

According to FIG. 2 For the production of the forming die 1, first the die core 2 is elastically elongated along the working movement axis 5 (method step (1) in FIG FIG. 2 ). As a result, the die core 2 receives, as the core cross-section QM, a mounting core cross section which is smaller than the useful core cross section.

Subsequently, fiber-reinforced plastic in the wet state is applied to the outside of the cross-section reduced die core 2 in such a way that an in FIG. 2 shown in a highly schematically illustrated reinforcing fiber structure 9 of the fiber-reinforced plastic with continuous fibers of carbon in the circumferential direction of the die core 2 about the working movement axis 5 (method step (2) in FIG FIG. 2 ). In the illustrated example case, the reinforcing fiber structure 9 with carbon continuous fibers is embedded in a thermoplastic matrix (for example polysulfone / PSU) of the fiber-reinforced plastic.

In still reduced cross-section die core 2 of the initially wet fiber reinforced plastic is annealed and thereby cured (step (3) in FIG. 2 ). After the fiber-reinforced plastic has hardened, the elongation of the die core 2 is canceled (method step (4) in FIG FIG. 2 ). As a result, the core cross section QM of the die core 2 increases to the utility core cross section. This results in a radial bias (arrows in the partial view (4) of FIG. 2 ) of the reinforcing body 3 produced by curing the fiber-reinforced plastic against the die core 2. The production of the forming die 1 is thus completed.

Notwithstanding the in FIG. 2 illustrated variant of the method for producing the forming die 1 is in the case of the manufacturing method according to FIG. 3 the reinforcing body 3 made separately from this before applying to the die core 2. For this purpose, fiber-reinforced plastic is applied to a mandrel 10 away from the die core 2 in the wet state such that the reinforcing fiber structure 9 of the fiber-reinforced plastic extends around it in the circumferential direction of the mandrel 10 (method step (1) in FIG FIG. 3 ). By tempering the initially wet fiber-reinforced plastic this is cured to form the Armierungskörpers 3. The hardened reinforcing body 3 is pulled off the mandrel 10 (method step (2) in FIG FIG. 3 ). In the interior of the hardened reinforcing body 3, where the mandrel 10 was previously arranged, the core receptacle 7 is formed, which has a core receiving opening 1 on both sides along the core receiving axis 8. As a core receiving cross-section QA, the core receptacle 7 of the Armierungskörpers 3 in this phase of the illustrated manufacturing method has an output core receiving cross section.

After the reinforcing body 3 has been provided as a hardened hollow body, the temperature of the reinforcing body 3 is changed, in the illustrated example, the reinforcing body 3 is cooled. Due to the corresponding temperature behavior of the carbon fiber reinforced plastic used here, the cooling leads to a widening of the reinforcing body 3 and, associated therewith, to an enlargement of the core receiving cross section QA of the reinforcing body 3 with respect to the starting core receiving cross section (step (3) in FIG FIG. 3 ). Thus, the reinforcing body 3 is ready for assembly.

To produce the assembly readiness of the die core 2, the die core 2 is cooled starting from its use state. As a result, the core cross section QM of the die core 2 is reduced relative to the use core cross section (step (4) in FIG FIG. 3 ). Thus, the die core 2 is ready to install.

The core cross-section QM of the ready-to-install die core 2 is smaller than the core receiving cross-section QA of the ready-to-fit Armierungskörpers 2, wherein the core cross-section QM of the ready Matrizenenkerns 2 in the vertical projection on the core receiving cross section QA of the ready Armierungskörpers 3 within the core receiving cross section QA of the ready-Armingskörpers 3.

After the assembly readiness of the reinforcing body 3 and the die core 2 is established, the reinforcing body 3 and the die core 2 are joined by inserting the ready-to-install die core 2 through one of the core receiving openings 11 of the reinforcing body 3 along the core receiving axis 8 into the core seat 7 of the reinforcing body 3 (operation (5) in FIG. 3 ).

After the die core 2 has assumed its desired position in the interior of the reinforcing body 3, the unit of reinforcing body 3 and die core 2 is heated (step (6) in FIG FIG. 3 ). Due to the heating, the core cross section QM of the die core 2 increases, while the core receiving cross section QA of the reinforcing body 3 decreases. As a result of the enlargement of the core cross section QM of the die core 2 with simultaneous reduction of the core receiving cross section QA of the reinforcing body 3, the reinforcing body 3 is prestressed radially against the female body 2. The production of the forming die 1 is completed.

Claims (8)

1. Method for producing a forming die (1) for pressure-forming workpieces, in which a die core (2) of the forming die (1) is provided at the outer side with a core reinforcement in the form of a reinforcement body (3) made of a fibre-reinforced plastics material in such a manner that the reinforcement body (3) arranged on the die core (2) surrounds the die core (2) in a peripheral direction of the die core (2) around a working movement axis (5) of the die core (2), along which working movement axis a workpiece receiving member (4) of the die core (2) extends inside the die core (2), wherein the reinforcement body (3) comprises a plastics matrix and a reinforcing fibre structure (9) which is embedded in the plastics matrix and which extends in the peripheral direction of the die core (2) wherein the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2) such that the core reinforcement which is arranged on the die core (2) is radially pretensioned transversely to the working movement axis (5) against the die core (2), and wherein the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2) by a core cross-section (QM) of the die core (2) which extends perpendicularly to the working movement axis (5) being decreased to an assembly core cross-section with respect to a core cross-section for use which is present in a state for use of the die core (2),
   characterised in that the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2)

   • by the fibre-reinforced plastics material in the non-hardened state being applied to the outer side of the die core (2) which has the assembly core cross-section in such a manner that the reinforcing fibre structure (9) of the fibre-reinforced plastics material extends in the peripheral direction of the die core (2) which has the assembly core cross-section and

   • by the core cross-section (QM) of the die core (2) being increased to the core cross-section for use after the hardening of the fibre-reinforced plastics material applied to the outer side of the die core (2).
2. Method for producing a forming die (1) for pressure-forming workpieces, in which a die core (2) of the forming die (1) is provided at the outer side with a core reinforcement in the form of a reinforcement body (3) made of a fibre-reinforced plastics material in such a manner that the reinforcement body (3) arranged on the die core (2) surrounds the die core (2) in a peripheral direction of the die core (2) around a working movement axis (5) of the die core (2), along which working movement axis a workpiece receiving member (4) of the die core (2) extends inside the die core (2), wherein the reinforcement body (3) comprises a plastics matrix and a reinforcing fibre structure (9) which is embedded in the plastics matrix and which extends in the peripheral direction of the die core (2) wherein the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2) such that the core reinforcement which is arranged on the die core (2) is radially pretensioned transversely to the working movement axis (5) against the die core (2), and wherein the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2)

   • by the reinforcement body (3) being produced as a hardened hollow member which has in the interior thereof a core receiving member (7) for the die core (2), wherein the core receiving member (7) of the reinforcement body (3) has a core receiving member axis (8) which extends along the working movement axis (5) of the die core (2) when the die core (2) is in the mounting position, wherein the core receiving member (7) of the reinforcement body (3) has along the core receiving member axis (8) a core receiving member opening (11) at least at one side and wherein, in an initial assembly state of the reinforcement body (3), the core receiving member (7) of the reinforcement body (3) has an initial core receiving member cross-section which extends perpendicularly to the core receiving member axis (8),

   • by a readiness for assembly of the reinforcement body (3) and the die core (2) being produced and

   • by the ready-for-assembly reinforcement body (3) and the ready-for-assembly die core (2) being joined, wherein the ready-for-assembly die core (2) is introduced through the core receiving member opening (11) of the ready-for-assembly reinforcement body (3) along the core receiving member axis (8) into the core receiving member (7) of the ready-for-assembly reinforcement body (3) and the reinforcement body (3) is thereby arranged at the outer side of the die core (2),
   characterised in that the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2)

   • by the readiness for assembly of the reinforcement body (3) and the die core (2) being produced by the core receiving member cross-section (QA) of the reinforcement body (3) being increased with respect to the initial core receiving member cross-section, wherein the core receiving member cross-section (QA) of the ready-for-assembly reinforcement body (3) has such dimensions that the core cross-section (QM) of the ready-for-assembly die core (2) is, in the perpendicular projection onto the core receiving member cross-section (QA), within the core receiving member cross-section (QA), and

   • by, after the reinforcement body (3) and the die core (2) have been joined so as to produce the radial pretensioning of the reinforcement body (3) against the die core (2), the core receiving member cross-section (QA) of the reinforcement body (3) being decreased.
3. Method according to claim 2, characterised in that the reinforcement body (3) is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2)

   • by the core cross-section (QM) of the die core (2) being decreased with respect to a core cross-section for use which is present in a state for use of the die core (2) for producing the readiness for assembly of the reinforcement body (3) and the die core (2), and

   • by, after the reinforcement body (3) and the die core (2) have been joined so as to produce the radial pretensioning of the reinforcement body (3) against the die core (2), the core receiving member cross-section (QA) of the reinforcement body (3) being decreased and the core cross-section (QM) of the die core (2) being increased.
4. Method according to any of the preceding claims, characterised in that the reinforcement body (3) made of fibre-reinforced plastics material is applied directly to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2).
5. Method according to at least claim 1 or claim 3, characterised in that the core cross-section (QM) of the die core (2) is decreased with respect to the core cross-section for use by the die core (2) being extended along the working movement axis (5) of the die core (2), preferably resiliently extended, with respect to the state for use.
6. Method according to at least claims 1 or claim 3, characterised in that the core cross-section (QM) of the die core (2) is decreased with respect to the core cross-section for use by the temperature of the die core (2) being changed with respect to the temperature in the state for use of the die core (2).
7. Method according to at least claim 2 or claim 3, characterised in that the core receiving member cross-section (QA) of the reinforcement body (3) is increased with respect to the initial core receiving member cross-section by the temperature of the reinforcement body (3) being changed with respect to the temperature in the initial assembly state of the reinforcement body (3).
8. Method according to any of the preceding claims, characterised in that a reinforcement body (3) made of carbon-fibre-reinforced plastics material is applied to the die core (2) so as to produce a radial pretensioning of the reinforcement body (3) against the die core (2).

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